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SBI3U Exam Review > Unit 1: Evolution - Natural Selection > Flashcards

Unit 1: Evolution - Natural Selection Flashcards

1
Q

When did Darwin return to England?

A

In 1936

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2
Q

What did Darwin do when he returned to England

A

Wrote papers describing his collections & observations

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3
Q

What did Darwin bring back?

A

Brought back thousands of specimens and fossils

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4
Q

What came out in 1844?

A

A draft of his theory of species formation

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5
Q

What was Darwin concerned about?

A

The impact of his ideas in a religious culture

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6
Q

What did Darwin instruct his wife to do?

A

Instructed his wife to publish this essay upon his death

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7
Q

What was Darwin reluctant to do?

A

To publish but didn’t want ideas to die with him

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8
Q

What happened in 1858?

A

Darwin received a letter that changed everything.

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9
Q

Who was the letter from?

A

Alfred Russel Wallace, a young naturalist working in the East Indies

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10
Q

What had Alfred Russel Wallace done?

A

Had written a short paper with a new idea.

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11
Q

What had he asked Darwin?

A

To evaluate his ideas and pass it along for publication.

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12
Q

What happened on November 24, 1859?

A

Darwin published “On the Origin of Species by Means of Natural Selection”

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13
Q

What was Darwin’s first idea?

A

Variation exists in natural populations

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14
Q

What was Darwin’s second idea?

A

Many more offspring are born each season than can possibly survive to maturity

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15
Q

What was Darwin’s third idea?

A

As a result, there is a struggle for existence - competition

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16
Q

What was Darwin’s fourth idea?

A

Characteristics that are beneficial in the struggle
for existence will tend to become more common in the population, changing the average characteristics of the population - adaptations

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17
Q

What was Darwin’s fifth idea?

A

Over long periods of time, and given a steady input of new variation into a population, these processes lead to the emergence of new species

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18
Q

What was Darwin’s first observation (Darwin’s Theory of Evolution by Natural Selection)?

A

Individuals within a species vary in many ways

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19
Q

What was Darwin’s second observation (Darwin’s Theory of Evolution by Natural Selection)?

A

Some variability can be inherited

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20
Q

What was Darwin’s third observation (Darwin’s Theory of Evolution by Natural Selection)?

A

Each generation produces way more offspring than can survive and passes on variations

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21
Q

What was Darwin’s fourth observation (Darwin’s Theory of Evolution by Natural Selection)?

A

Populations tend to remain stable in size

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22
Q

What was Darwin’s first inference (Darwin’s Theory of Evolution by Natural Selection)?

A

Members of the same species compete with each other for survival

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23
Q

What was Darwin’s second inference (Darwin’s Theory of Evolution by Natural Selection)?

A

Individuals with more favourable variation are more likely to survive. SURVIVAL IS NOT RANDOM

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24
Q

What was Darwin’s third inference (Darwin’s Theory of Evolution by Natural Selection)?

A

Survivors contribute proportionately more offspring to succeeding generations the favourable variation will become more common THIS IS NATURAL SELECTION

25
Q

Why did people not believe Darwin’s theory?

A

Not everyone thought the earth was millions of years old

26
Q

What did fossil records have?

A

HUGE gaps (geology and palaeontology are new sciences)

27
Q

What did fossil records now show?

A

Transitional forms

28
Q

What did people not know about?

A

Genetics

29
Q

What has life on earth been dated at?

A

3.5 billion years

30
Q

Today, how many more fossils have been found?

A

Far more fossils found which show progression

31
Q

What do we understand today?

A

Genetics, mutations, and recombination - this gives the most compelling evidence

32
Q

What happened in 1866?

A

Gregor Mendel publishes work on peas (ignored until 1900s)

33
Q

What came from the idea of Natural Selection?

A

Two results or theories (to further study)

34
Q

What are these two results or theories called?

A

Descent with Modification
Common Descent

35
Q

What is Descent with Modification?

A

Each living organism has descended, with changes from other species over time

36
Q

What is Common Descent?

A

Were derived from common ancestors

37
Q

What is Natural Selection?

A

A mechanism of evolution where by traits become more or less common in a population due to effects on survival and reproduction

38
Q

What are the four types of natural selection?

A

1.Directional Selection
2.Stabilizing Selection
3.Disruptive Selection
4.Sexual Selection

39
Q

What is directional selection?

A

Selection that favours an increase or decrease in the value of a trait from the current population; favours the phenotypes at one extreme over another.

40
Q

What is stabilizing selection?

A

Selection that favours intermediate phenotypes and acts against extreme variants

41
Q

What is one example of stabilizing selection?

A

Human babies have an average size
Too big and they can’t get through birth canal
Too small and they have low survivability

42
Q

What is disruptive selection?

A

Selection that favours two or more variations of a trait that differ from the current population average

43
Q

What can disruptive selection lead to?

A

New species forming

44
Q

What is mimicry?

A

Similarity of one species to another which provides protection

45
Q

What are some mimicry similarities?

A

Appearance, behaviour, sound, scent

46
Q

What is sexual selection?

A

Differential reproductive success caused by variation in the ability to obtain mates

47
Q

What does sexual selection result in?

A

Results in sexual dimorphism, and mating courtship behaviours

48
Q

What is sexual dimorphism?

A

A phenotypic difference between males and females of the same species

49
Q

What phenotypic differences result from sexual dimorphism?

A

Morphology
Ornamentation
Behaviour

50
Q

What is one example of sexual selection?

A

Female Mate Choice: Females choose mates based on physical traits, such as bright colouration and behaviour

51
Q

What is another example of sexual selection?

A

Male-versus-male competition = males have physical features that assist them in establishing control of and defending their territory used in direct competition

52
Q

What are some changes in the genetic makeup of a population NOT?

A

Influenced by the traits of individuals

53
Q

What are examples of evolutionary change without selection?

A

1.Genetic Drift
2.Bottlenecks and Founder Effect

54
Q

What is Genetic Drift?

A

Changes to allele frequency as a result of chance are much more pronounced in small populations

55
Q

What happens when populations are small?

A

Chance can play a significant role in altering allele frequencies.

56
Q

What is a genetic bottleneck?

A

A dramatic, often temporary, reduction in population size, usually resulting in significant genetic drift

57
Q

What is the founder effect?

A

Genetic drift that results when a small number of individuals separate from their original population and establish a new population

58
Q

What is a human example of the founder effect?

A

Polydactyly (extra fingers and toes, a symptom of Ellis-van Creveld syndrome) are more common in Amish communities in the US

59
Q

Why is Polydactyly more common in Amish communities in the US

A

This is because they have grown from a very few founders, have not recruited newcomers, and tend to marry within the community

SBI3U Exam Review (5 decks)

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